A Conservative Party spokesman said: "It was not our intention to misrepresent by using this headline copy with the news link, where the BBC's £7bn figure is clearly displayed, but we are reviewing how our advert headlines match accompanying links."

Clicking on the advert took readers to the original story on the BBC News website by Sean Coughlan, where it had the headline "Multi-billion pound cash boost for schools".

BBC analysis in the story from 30 August queried the government's claims about its additional funding for schools.

The corporation's head of statistics, Robert Cuffe, explained here that the government was not calculating the spending increase in the usual way.

"Describing this as a £14bn increase would make the government seem more generous than it is in fact being," he wrote.

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The Tory Facebook advert featured a link to a BBC story

The spending announcement provided an extra £2.6bn next year, £4.8bn the year after that and £7.1bn in 2022-23.

Added together that makes £14bn, but it is not how spending increases are normally worked out, Mr Cuffe said.

Because budgets are normally discussed for individual years, he said the usual practice is to measure the spending increase for one year - usually the last where the increase is the largest.

Mr Cuffe told the BBC: "Independent experts look at the effect of spending increases on a department's annual budget.

"Adding up those increases over many years exaggerates the government's generosity. It is an old trick of political accountancy that many governments have used."

In his spending review announcement in Parliament on 4 September, Chancellor Sajid Javid used the smaller figure.

He said: "Today we are delivering on our pledge to increase school spending by £7.1 billion by 2022-23, compared with this year."

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The BBC posted the story on Facebook with its own headline

Full Fact said that various versions of the advert with the altered headline had received between 222,000 and 510,000 impressions - although these can include multiple viewings by the same person.

The Facebook adverts - which started running on 2 September - have since been deactivated.